Fig. 79.

Fig. 8o.

When the die-forging is circular in shape, then it may be fixed as shown in figs. 79 and 80, by means of either two or three set-screws, which press upon the taper sides of the die. The three set-screws permit the die to be centred accurately in place very readily. The bolster may be either circular in shape or rectangular, and fixed to the machine, as. shown in fig. 77 or fig. 78. In the plan illustrated in fig. 77

Fig. 81.

it is advisable to make the bolt holes in the form of slots, so that the toolsetter may have some freedom in adjusting the bolster in place. Washers should be placed under the head of the screw, so that the pressure due to tightening up may be distributed evenly.

Fig. 82.

A point of some importance to watch in the equipment of a workshop in which a number of presses are in use is the size of the dies and punches, so that as far as possible they may be interchangeable. Unless this is done much time will be wasted because a particular press is engaged in the execution of an order and cannot be stopped. In order that any machine of a group may be utilised, the stroke of the rams and the depth between the ram and the bed must in each case be noted, and the diameter and length of the punches determined to suit. If there is much variation in depth, then it may be necessary to construct some adapters to compensate for these differences. The tools should be constructed to suit the smallest machine, and for each of larger presses a plain chuck or false nose would be formed with a shank to suit the larger hole in the ram, and provided with a hole to take the standard punch. In the case of the die a special bolster would be required, the lower face or bottom being shaped to suit the press bed, whilst the upper part would be machined to take the standard die. By arranging the thickness of the bolster and the length of the false nose any variation of depth in the frames can easily be compensated for.

By these means the shop foreman can easily arrange matters so that the machines are utilised uniformly, even when an unexpectedly heavy demand arises for some special article, the execution of which would be delayed-seriously, possibly-if only one press was available for that particular operation. An example of this interchange of tools can be seen in figs. 81 and 82; in the former is shown a punch and die fixed in a press of proper size, whilst in fig. 82 the same size punch and die are shown fixed in a larger press by means of a false nose F N, and a thick bolster B, thus enabling the standard punch and die to be used, and the same sized blanks to be produced simultaneously at several presses.